U.S. Pat. No. 6,504,317 B1 discloses a ceiling lamp brightness control device for adjusting brightness of a ceiling lamp with a zipper switch. The zipper switch includes a zipper, a conductive ring and a plurality of conductive pieces. By pulling the zipper, the conductive ring is driven to rotate to come into contact with at least a selected one of the conductive pieces. Accordingly, each time the zipper is pulled, a different resistor is conducted and a different resistance is exhibited. Thereby, the brightness of the ceiling lamp can be adjusted in steps. However, the steps are discrete and limited in number.